How well does contralateral testis hypertrophy predict the absence of the nonpalpable testis?

We assessed the accuracy of contralateral testis hypertrophy for predicting monorchia in patients with a nonpalpable testis.

From May 1993 to September 1998 we evaluated 60 patients 7 months to 11 years old for a unilateral nonpalpable testis. Four patients were excluded from study who had received human chorionic gonadotropin or had signs of puberty. We correlated contralateral testis hypertrophy, defined as testis volume greater than 2 cc or testis length greater than 2 cm., with presence or absence of the nonpalpable testis. We also recorded the degree to which contralateral testis length less than 2.1 cm. correlated with the presence or absence of the nonpalpable testis. Laparoscopy and open exploration were performed in 52 and 4 cases, respectively.

Contralateral testis hypertrophy greater than 2 cm. was noted in 16 patients, including 14 (87.5%) with monorchia and 2 (12.5%) with an intra-abdominal testis. Of the 15 patients with a contralateral measurement of 1.8 to 2.0 cm. 14 had monorchia (93%) and 1 had a tiny ovotestis. Of the 25 patients with a contralateral measurement of less than 1.8 cm. 13 (52%) had testes that were intra-abdominal in 11 and canalicular in 2. The optimal cutoff value for contralateral enlargement was 1.8 cm. (p = 0.00061). The most common laparoscopic finding in patients with contralateral testis hypertrophy greater than 2 cm. was blind ending vessels proximal to the internal ring in 56%.

Contralateral testis hypertrophy is common in patients with a nonpalpable testis. Hypertrophy 1.8 cm. or greater predicts monorchia with an accuracy of about 90%. The finding of contralateral testis hypertrophy provides useful information for preoperative counseling, allowing us to inform parents that the nonpalpable testis is most likely absent. Exploration is still required. Laparoscopy is particularly advantageous in contralateral testis hypertrophy since it was the only procedure required in about half of our cases.